Method of making steel rule blanking dies and punches



R. J. TOBEY June 7, 1960 METHOD OF MAKING STEEL RULE BLANKING DIES ANDPUNCHES Filed Feb. 17, 1958 ill FIG.

illll INVENTOR. RUSSELL J. TOBEY ATTORNEY marked by the die.

atent ice 2,939,347 Patented June 7, 1960 States This invention relatestoblanking dies and punches and more specifically to a method of makingsteel rule blankingdies and punches for use therewith.

, years, effortshave been 'made to reduce the ex.-

' pense of making blanking'die's and punches. One of the results'ofitheseeffortshas been the development of steel B A KI TG dies, whichhave substantially reduced the seamen-Se p'er'unitfor comparativelyshort production runs. Prior to the present invention, punches for usewith such dies have been manually filed after being Successful formingof the punch has been dependent on human skills. To make a punch whichwill hold up even during comparatively short production runs of 50,000to 100,000 has required the use of expensive tool steel. Because of highcost of tool steel, large-area punches have generally been formed insections along the periphery of the pattern and the sections fittedtogether. It has also been necessary to make separate punches fordifferent thicknesses of metal to be blanked.

It is a primary purpose of the present invention to provide a method ofmaking steel rule blanking dies and punches which is inexpensive and notdependent on skilled diemakers in forming the punches. It is a furtherobject of the present invention to provide a method of making such' diesand punches which will hold up during intermediate length productionruns and which will permit the use of metal less extensive than toolsteel in the punch. An additional purposeis to provide a method ofmaking such dies and punches wherein the forming of the punch is notdependent on the thickness of the metal to be blanked. Other objectswill be apparent from this specification.

Referring to the drawings:

Figure l is an exploded perspective illustrating the application of myinvention to a die and punch set for blanking oval parts- The first stepin my method is the forming of a template '10 to the shape of the partto be blanked. For a simple die and punch set, as contrasted to acompound die and punch set, this template will also be a template of thepunch to be made. The punch template 10 may be formed of a wide varietyof metals having various thicknesses, but is preferably formed of mildsteel approximately thick because of the ease with which such sheetmetal may be cut. The forming of the template may be accomplished byknown methods, as by sawing to the desired shape.

A steel rule dies 17 is then shaped closely around punch template 10.This may be accomplished by placing punch template 10 on a die board 11,scribing a mark 12 along its edge, cutting a plurality of. slots 13 indie board 11 along the scribed mark 12, replacing template 10 on dieboard 11, and fitting a steel rule cutting blade 14 closely aroundtemplate '10 and driving it into slots 13. The die board 11 may be madeof maple approximately thick, or of any other material of suitablethickness now in use for such die boards.

I prefer to cut several slots through the die board, leaving the portionof the die board within the scribed mark 12 joined'to the balance of thedie board by several bridging portions. This requiresthe cutting ofnotches 16 in thesteel' rule cutting 'blade'14 to fit the bridgingportions between the slots 13. To obtain a tight driving fit,

it is preferable that s1ots'13 be. narrower than steel rule14. V

While any suitable steel rule. cutting blade may be used withoutdeparting fromjmy invention, I find that for most applications an ,8'or'10 pointjrule, 1" or 1%" wide, is'desirable. It is usually advisable toshape steel rule cutting blade14 roughly to template 10 and temper itprior, to fitting it closely around template 10 and inserting it intoslots 13 of. die b'oard'll. The steel rule 14 is driven into slots 13soythat its cutting edge 15 projects from die board 11.. The cuttingedge 15 of the steel rule, 14 j preferably tapers inward toward thetemplate 10 and ordinarily is somewhat flatted, depend- 7 ingonthecornposition and thickness of the metalto be blanked. i i

*The'die 17 and punch template 10 are then removably secured inalignment with each other to opposing holders 18 and 19 of a die set,also called die and punch shoes; and a piece of metal 30 larger thantemplate 10 is removably secured to the same die set member as template10 so as to cover the outer surface of template 10 completely. Die setholders are customarily provided with means for aligned attachment to apunch press, not shown, and one of such holders is provided withaligning pins 20 and the other with corresponding bushings 21. Thetemplate 16 and die 17 are secured respectively to back-up plates 22 and23 with screws 24 and 27; then the back-up plates 22 and 23 are securedto such holders 18 and 19 with bolts 25 and 28 and nuts 26 and 29.

The piece of metal 30 will be blanked to form a punch, as will behereinafter more fully explained. It may be of various compositions andthicknesses, but -I have found that for most applications, an unannealedsteel alloy, such as chrome molybdenum, of approximately /8" thickness,is suitable. The piece of sheet metal 30 has holes bored into or throughit in alignment with screws 24, which project through template 10 andsecure sheet metal 30 to back-up plate 22 so as to cover template 10.

After the die 17, template 10 and sheet metal 30 have been thus securedto the die set members 18 and 19, I strike sheet metal 30 with "thesteel rule cutting blade 14, with sufficient force to blank sheet metal30 between such steel rule cutting blade and template '10. I thus form apunch, not shown, having outer edges substantially coterminous with theinner edges of the cutting blade 14. The striking may be most readilyaccomplished by attaching holders 18 and 19 to a punch press in theusual manner and activating the punch press with adequate pressure. Ifind that the pressure required is slightly greater than would berequired to blank sheet metal 30 with a standard steel rule blanking dieand punch set.

After the punch has been blanked out of sheet metal 30, the punch andthe template 10 are removed from back-up plate 22, template 10 isdiscarded or stored, and the punch resecured to back-up plate 22. Thesteel rule blanking die and punch set is then ready for use.

It will be recognized that the suitable ranges of the composition andthickness of sheet metal 30 and template 10, the thickness and width ofsteel rule cutting blade 14, and the dgeree of flatting of cutting edge15 are determined by the strength and thickness of the material to beblanked. Generally as the strength and thickness of the metal to beblanked increases, the thickness and strength of the punch requiredincreases, the thickness and degree of fiatting of the steel ruleincreases, and the a aryi h stee rule be w 7 h de ee flat n f t e t 'ecg appli t n f my i e sim e fi mpl i 34 R eh i "w ll o o f i d skjlll lili fl 3X may. c d y 'adla l ei IQ mman a required thickness of thepunch templateincreasess How ever," where the punch'template is made ofA 'f rnild steel and the"pun ch of Ms chrome molybdenum steel,

most metals A" thick or. less can be accommodated by '7 1 have; nmsea"andae mfxe sets, without departing f rom fiiyiinv entidn. 7 H v g h sescr e my ent n, 1 claim; a

' Jand to b nati n b a ingmt plqrq t ri tii ipuu i" 1;; A method for maing a steel rule: blanking ie and punch set haying.substantiallgtcoterrn nous inner. die.1 5 edges and outerfpunch edgesisaidgmethodcomprising thel steps of forming a punch template out ofsheet metal,

n i i ste fi utt n ij'rblad ii to i -w d,

1 6 3 Qu' d' ai 9 mb emp e, i fi o' b ly an alignecll'y" securing 'saidjsteel rule a cutting blade and said punch template to thejlopposedmembers of a die. set rem sf min rger l' etofi'sheet metal o we of;said. d e. t m nlier hi l s d p ch temp ate; nd

Bl k a Punc q t o aid a np b i i e metal with said steel rule cuttingblade and punch template. a

2-. A m th q m ing.- uwq r le bl nk ng d e n 8 and Q nta cl ayy g 2703,9 1 f 25 21731. 3 Bite j 2 821,871

scribing amark along the edge of said punch template on a dieboard,rcutting a*p1ura1ity of slots along said mark, fitting a steelrule cutting blade closely around said punch template into said slots,securing over said punch template 'to, a die set menalgegia: largerpiece 'of thicker shee metalsmqunt ilg saidsteelmle u tiue ladetow heopl' dsiligfdieflsetkmerpbertalignedlygi i'espect'to said punchtemplate, and'striking said-thicker pieceof sheet metalz'iyith Saidsteelrule cutting :Vblagle til-blank out a V punch." a

3. The methoddefined 111 alas; 1,?tgether with the further steps ofremoving the punch tengplate from the die set member to which "it was'so secureiand'then securing the blanked-out punch directly thereto. J

R l exeucesCitqd in diefile g higr 1 A ES PATENTS 21 54.221 L'Ianj.14;1950 anew .Ded- 2A 19.52

Mar. 1, 1955 May 3-19. 7 F b 7 3

